Additive manufacturing may be used to quickly and efficiently manufacture complex three-dimensional components layer-by-layer, effectively forming complex components. Such additive manufacturing may be accomplished using polymers, alloys, powders, wires, or similar feed stock materials that transition from a liquid or granular state to a cured, solid component.
Additive manufacturing is typically accomplished by several technologies that rely on feeding polymer materials through a nozzle that is precisely located over a preheated or unheated substrate. Parts are manufactured by the deposition of new layers of materials above the previously deposited layers. Unlike rapid prototyping processes, additive manufacturing is intended to produce a functional component constructed with materials that have strength and properties relevant to engineering applications. On the contrary, rapid prototyping processes typically produce exemplary models that are not production ready.
Heating of the feed or filler material in the nozzle in additive manufacturing is generally accomplished by direct contact between a polymer feed stock and a heating element, typically a resistively heated metal cylinder at elevated temperatures. Likewise, in additive manufacturing, unlike rapid prototyping, the entire component under construction is typically maintained at an elevated temperature in a chamber or furnace until the build is complete. Keeping previously deposited layers at elevated temperature improves the adhesion between the component and newly deposited material while minimizing macroscopic distortion. There are inherent limitations to this technology that prevent higher deposition rates, out of furnace printing and control of microstructural defects (such as pores).
In addition, existing additive manufacturing processes, including polymer extrusion based deposition for additive manufacturing (PeD), typically exhibit a thermal lag associated with heating a deposition nozzle. Typical PeD systems obtain thermal stability by maintaining a massive resistive heater at a constant temperature resulting in slow response. This makes accurate control of the flow difficult and prevents the building of advanced structures that require transient deposition rates and frequent interruptions in flow (in a mechanism analogous to image generation in an ink jet printer).